As interest in environmental protection is increased in recent years, photovoltaic power generating systems having lower environment load have come to attention. To get the photovoltaic power generating systems widespread use, cost reduction is considered.
For reducing the cost, it is proposed to provide a solar cell module of frameless (sashless) structure, or to increase an area of a power generator of the solar cell module. However, these proposals may cause deterioration of the strength. For example, since the solar cell module of frameless structure has low rigidity, the module easily bends, and the solar cell module is easily broken. If the area of the solar cell module is increased, a wind pressure and a snow accumulation load applied to one sheet of solar cell module are increased. Therefore, like the case of the solar cell module of frameless structure, a bending amount of a light-receiving surface of the solar cell module is increased, a transparent substrate easily falls off, and a crack is easily produced in the solar cell element.
To solve this problem, it is proposed to dispose a supporting member that supports a central part of the solar cell module (e.g., refer to Japanese Patent Application Laid-Open Nos. 2004-087884 and 2003-105940).
According to the above conventional techniques, however, since the supporting member is provided such that it is in contact with a non-light-receiving surface of the solar cell module, an absolute value of bending moment that is applied to the solar cell module becomes maximum in a central part that is the supporting part. Therefore, when a positive pressure load is applied, stresses are concentrated on the central part. That is, a radius of curvature of the solar cell module surface becomes small and abrupt bending is produced. If the radius of curvature becomes smaller than a certain limit value, the solar cell module is broken due to a fracture of the transparent substrate, a crack of the solar cell element or the like.
Further, since the solar cell module and the supporting member axe in a state where they abut against each other, there is a problem that flow (ventilation) of air along a back surface of the solar cell module is hindered, and heat of the solar cell module cannot be sufficiently radiated.
There is an adverse possibility that water such as rain water is remained in the abutted part. In this case, there is an adverse possibility that the back surface protection material used for the solar cell module is deteriorated due to remain of water for a long time. If water permeates through the back surface protection material, ethylene vinyl acetate (EVA) that is used as filler for sealing the solar cell element absorbs water to generate acetic acid, and there is an adverse possibility that a wiring member is damaged.